How to load localization files from URL?

Does anyone know how to load localization files from a server via a URL?

Docs say this:

You can also localize your application from your server using URL directives based on the current locale as set by the user.
But I do not understand what that means or how it is supposed to work.

A colleague mentioned, that it might mean, that you do localization without using:

tr(..)

altogether. is that the case?